Determination of Hydroxamic Acids by Thermal-Lens Spectrometry

Conditions are determined for the determination of salicylhydroxamic and acetylhydroxamic acids by thermal-lens spectrometry using iron(III) in an aqueous medium. The detection limits are 6 × 10^–8 and 3 × 10^–8 M, respectively. The sensitivity can be enhanced 3–6 times with the use of aqueous–organic media.     

Localization of nonlinear waves in elastic bodies with inclusions

By the example of the problem of the motion of a semi-infinite string lying on an elastic base, a method for describing wave localization near inclusions is proposed for the case of a cubic nonlinearity of the base. The method applies the perturbation technique to the amplitude of a localized mode. The nature of the divergences is revealed, and the secular terms are found to belong to one of two types: inphase or antiphase with the localized wave. It is shown that a combination of the renormalization method and multiscale method provides a convergence of the solutions, which are sought for in the form of power series in the amplitude of the localized mode. It is found that the localization process is determined by the type of the discrete spectrum, type of the nonlinearity, and type of dispersion. The nonlinearity of the elastic base produces two characteristic effects. First, the frequency of the localized wave becomes dependent on the wave amplitude. Second, the system can generate traveling waves at multiple frequencies, which withdraw energy from the localized wave and cause it to decay. The decay behavior is determined by the minimum frequency of these traveling waves (because it must be higher than the cutoff frequency). The lifetime of the localized wave as a function of the mass of a dynamic inclusion exhibits a number of maxima. In particular, the first maximum corresponds to the minimum amplitude of the traveling wave at the triple frequency.     

Gas-liquid chromatography of perfluorocarboxylic thioesters

Perfluorocarboxylic thioesters R_FC(O)SR (R_F=CF₃(CF₂)_j, R=CH₃(CH₂)_i, i andj=0–5) were studied for the first time by GLC on packed columns using SE-30, SKTFT-50X, and XE-60 as the stationary phase. The values of thermodynamics functions of sorption were calculated. The correlations between these functions and the molecular structures as well as the conditions of analysis were established. The insertion of the S atom into the molecules of derivatives of perfluorocarboxylic acids causes a decrease in the contribution of the orientation interaction and an increase in the dispersion interaction of thioesters with the stationary phases compared to esters and amides of perfluorocarboxylic acids studied previously. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1165–1168, June, 1997.     

Electrochemical Preconcentration of Iodide and Its Determination by Cathodic Stripping Voltammetry

The effects of some factors (the nature and structure of organic compound R, the nature of the electrode material, the composition and concentration of the supporting electrolyte, the potential and time of electrolysis) on the formation and dissolution of electrochemical concentrates of the composition I₂BrR were studied. The results obtained were used for determining iodide by cathodic stripping voltammetry in the concentration range of 6 to 500 g/L. The detection limit for iodide was found to be 0.2 g/L at an electrolysis time of 3 min.     

Gas-liquid chromatography of thioesters of perfluorocarboxylic acids 1. Characteristics of retention

Retention of thioesters of perfluoropentanoic acid C₄F₉C(O)SR was studied by GLC on packed and capillary columns using stationary phases SE-30, SKTFT-50X, XE-60, and Carbowax 20M. The retention indices of these compounds were calculated, and their relationship with the structure of the compounds and the conditions of the analysis were established. Translated fromIzvestiya Akademii, Nauk. Seriya Khimicheskaya, No. 5, pp. 984–986, May, 1997.     

Influence of ammonia on propane oxidation over a gallium-antimony oxide catalyst

The influence of ammonia on propane oxidation over a Ga–Sb oxide catalyst has been studied. Acrylonitrile is formed upon the interaction of acrolein with partially dehydrogenated ammonia. Ammonia increases the rates of overall and selective oxidation of propane. This is assumed to be due to the formation of electron-donor sites promoting proton separation from the propane molecule.

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. , . . , , .

     

IR spectroscopic studies of adiponitrile and ammonia adsorption over Ti?Sb?O catalyst

Rate constants for the aminolysis of o-(2,4-dinitrophenyl) cyclopentanone oxime with several primary alkylamines, C₂H₅NH₂–C₆H₁₃NH₂ and one secondary arylamine, purrolidine, in 11 water-acetonitrile are reported. With primary amines, base catalysis is absent, while with pyrrolidine saturation catalysis has been observed. Reduction in size of nonconjugated oxime moiety (leaving group), drastically decreases the rates. Thermodynamic parameters for these reactions have also been calculated.

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O-(2,4-) (C₂H₅NH₂–C₆H₁₃NH₂) , , : =11. , . ( ) . .

     

Synthesis of (α-substituted α-aminophosphinic and α-aminophosphonic acids

The reaction of ketoximes with hypophosphorous acid resulted in previously unknown -substituted--aminophosphinic acids, which were oxidized into the corresponding -substituted--aminophosphonic acids.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2729–2732, November, 1996.     

Reaction of asymmetric organomercury compounds with thallium trichloride

Summary Thallium trichloride exchanges two of its halogen atoms only for a radical that possesses a trans-configuratlon in cis-trans compounds, or for a radical that experiences electrophilic attack by the hydrogen ion in the decomposition of RHgR' by hydrochloric acid.     

Promoting effect of potassium on catalytic and surface properties and phase commposition of catalysts for synthesis of alcohols

The dependence between catalytic and surface acid-base properties of Zn–Cr–K catalysts has been established. Modification by potassium and an increase in potassium concentration promotes Zn–Cr–K reduction and raises the yield of higher alcohols. The spinel structure of catalysts is preserved.

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Zn–Cr–K . Zn–Cr–K , .